Processed cereals have been made for many years. In fact, corn flakes were first made by health enthusiasts as early as the late nineteenth century in Battle Creek, Mich. Additionally, minimally processed grain cereals including oats, corn, wheat and rice have been used for breakfast meals as well, e.g., oatmeal. More recently, puffed processed cereals made from both dough and grains as well as baked processed cereals such as cookie based processed cereals have also been made.
A method of making flaked processed cereals such as corn flakes is as follows. First, corn kernels are selected to meet minimum requirements. Considerations such as color (yellow), moisture and lack of the presence of contaminants are all considered. For example, kernels that have sprouted, are moldy, diseased or otherwise damaged are generally rejected. The selected corn kernels are then steamed to soften the grain so that the germ and husk may be removed. The remaining portion or grit is then cooled and dried. Raw grit is placed in a pressure cooker where vitamins, niacin, riboflavin, thiamin, minerals such as iron or other additives are included. Preservation of iron additives is especially important because much iron is lost in the processing of the corn kernels. The grits are passed through a dryer to reduce moisture. The moist warm flakes are then milled and toasted for a few minutes until crisp in texture and golden brown in color. The flakes are then cooled and packaged.
Another variation of the method stated above involves the step of adding vitamins, minerals, etc., to milled grains themselves. Under those conditions, the grain flour and vitamin/mineral powders are mixed together and the blend is hydrated for baking. In both of the aforementioned methods, the vitamins and minerals are incorporated throughout the flakes. However, providing a mineral coating for processed cereals is another possible way to fortify processed cereals. One reason this technique is not as popular is that there are some practical limitations to using a coating compared to admixing vitamins/minerals into the flour or dough used to make the flakes. Vitamins and minerals that are admixed into the flakes are better protected, there is better dispersion and there is less of a chance that the vitamins and minerals will be washed away by mixing the coated cereal with milk prior to consumption.
A method of preparing puffed grain processed cereals is as follows. Grains, such as wheat, are selected based upon size, moisture percentage, protein content and lack of the presence of contaminants. The grain is then cleaned to remove unwanted contaminants. The essence of puffing is to gelatinize the starch present in the grain in a hot pressure chamber and then suddenly release the pressure. This causes the grain to expand to several times i-s original size. The pressure chamber is sometimes referred to as the "gun" and releasing the pressure is sometimes referred to as "firing the gun." The expanded grain, also known as "berries," are separated from loose or broken kernels. To the berries, vitamins and other minerals are then added. The fortified berries are hot air oven dried to reduce the moisture and to obtain a predetermined puffed grain size.
Puffed dough processed cereals or other extruded grain dough cereals are made in a similar manner to the aforementioned methods. First, dry ingredients, including vitamins and minerals, are hydrated into a flowable paste. The dough or paste is placed in an extruder where it is put under heat and pressure. Dies are used to shape the dough. Air may optionally be injected if a lighter or less dense processed cereal puff is desired. For example, Cheerios.RTM. are a heavier oat dough puffed processed cereal and Rice Crispies.RTM. are a lighter rice dough puffed processed cereal. Further, other extruded dough cereals include such things as nuggets which are more dense and shredded wheats.
Fortification of processed cereals is also well known in the art. As mentioned, such items as vitamins, minerals, niacin, riboflavin, fiber, thiamin and other additives may be included. These fortificants may be added in various ways. First, heat tolerant vitamins may be incorporated into the processed cereal dough prior to cooking and second, heat sensitive or heat labile vitamins may be sprayed onto the finished processed cereal product after pelleting/shaping, drying and/or toasting. Either method and resulting processed cereal piece may be desirable depending upon the application.
In order to topically apply vitamins, a group of desired vitamins and/or minerals are pre-mixed and dissolved into a solution. The solution is then sprayed onto the respective processed flaked pieces, puffed cereal grain kernels, puffed dough pieces, extruded dough pieces, baked pieces, nuggets, rolled grain pieces, etc. By spraying the vitamin/mineral solution onto the various processed cereal pieces after the steps of drying, toasting, baking, etc., degradation of heat sensitive vitamins is prevented. However, topical application of a vitamin solution has disadvantages as well. A processed cereal is more likely to be unpalatable when topical vitamin/mineral coatings are applied. As such, attempts have been made to mask this unpalatable flavor by applying a frosting coating subsequent to the vitamin/mineral coating. However, this process may actually dilute the vitamin/mineral content of the previous coating. Examples of processes for topical application include: U.S. Pat. No. 5,250,308 which discloses a method and product resulting from topical application of fiber to foodstuff such as puffed snack products; U.S. Pat. No. 3,767,824 which discloses a method of coating processed cereal products with vitamins; and U.S. Pat. No. 2,775,521 which discloses a method for fortifying grain products with dry mixtures of vitamins and minerals using a coating process.
Conversely, heat tolerant vitamins may be incorporated into processed cereal dough prior to cooking by admixing dry vitamins and/or minerals with milled grains. In U.S. Pat. No. 4,478,857, a process of making nutrient fortified cereal based food is disclosed. In that disclosure, processed cereal grains are milled to a fine flour and then are admixed with vitamins and minerals in excess of recommended daily requirements. The vitamin/mineral enriched flour is then hydrated in preparation of being cooker extruded. There, gelatinization occurs where the processed cereal is shaped/sized and dried. The result is not only a vitamin enriched processed cereal, but a shelf stable product as well. Other patents using similar technology include: U.S. Pat. No. 2,345,571 which discloses processes for producing a vitamin fortified dry product by adding a fat soluble vitamin to composition to an aqueous slurry of vegetable material; and U.S. Pat. No. 1,575,762 which discloses a method of adding dry vitamins to bread dough.
Next, turning to alternative fortificants, the use of chelates, particularly amino acid chelates, is an effective way to increase bioavailability in warm blooded hosts. The term "chelate" has often been misunderstood or applied in a general or catch-all fashion. A chelate is a definite structure resulting from precise requirement of synthesis. Proper conditions must be present for chelation to take place, including proper mole ratios of ligands to metal ions, pH and solubility of reactants. For chelation to occur, all components should be dissolved in solution and either be ionized or of appropriate electronic configuration in order for coordinate covalent bonding between the ligand and the metal ion to occur.
Chelation can be confirmed and differentiated from mixtures of components by infrared spectra through comparison of the stretching of bonds or shifting of absorption caused by bond formation. As applied in the field of mineral nutrition, there are two allegedly "chelated" products which are commercially utilized. The first is referred to as a "metal proteinate." The American Association of Feed Control officials (AAFCO) has defined a "metal proteinate" as the product resulting from the chelation of a soluble salt with amino acids and/or partially hydrolyzed protein. Such products are referred to as the specific metal proteinate, e.g., copper proteinate, zinc proteinate, etc. This definition does not contain any requirements to assure that chelation is actually present. On the basis of the chemical reactant possibilities, there are some real reservations as to the probability of chelation occurring to any great degree. For example, the inclusion of partially hydrolyzed proteins as suitable ligands and the term "and/or" in reference to such ligands implies that products made solely from partially hydrolyzed protein and soluble salts would have the same biochemical and physiological properties as products made from combining amino acids and soluble metal salts. Such an assertion is chemically incorrect. Partially hydrolyzed protein ligands may have molecular weights in the range of thousands of daltons and any bonding between such ligands and a metal ion may be nothing more than a complex or some form of ionic attraction, i.e., the metal drawn in close proximity to carboxyl moiety of such a ligand.
While some products marketed as metal proteinates during the 1960's and 1970's may have been chelates, this was prior to the adoption of the AAFCO definition. An analysis of products currently marketed as metal proteinates reveals that most, if not all, are mixtures of metal salts and hydrolyzed protein or complexes between metal salts and hydrolyzed protein. Most are impure products which are difficult to analyze and are not consistent in protein make-up and/or mineral content.
The second product, referred to as an "amino acid chelate," when properly formed, is a stable product having one or more five-membered rings formed by reaction between the carboxyl oxygen, and the .alpha.-amino group of an .alpha.-amino acid with the metal ion. Such a five-membered ring is defined by the metal atom, the carboxyl oxygen, the carbonyl carbon, the a-carbon and the .alpha.-amino nitrogen. The actual structure will depend upon the ligand to metal mole ratio. The ligand to metal mole ratio is at least 1:1 and is preferably 2:1 but, in certain instances, may be 3:1 or even 4:1. Most typically, an amino acid chelate may be represented at a ligand to metal ratio of 2:1 according to the following formula: ##STR1## In the above formula, when R is H, the amino acid is glycine which is the simplest of the .alpha.-amino acids. However, R could be representative of any other of the other twenty or so naturally occurring amino acids derived from proteins. These all have the same configuration for the positioning of the carboxyl oxygen and the .alpha.-amino nitrogen. In other words, the chelate ring is defined by the same atoms in each instance. The American Association of Feed Control Officials (AAFCO) have also issued a definition for an amino acid chelate. It is officially defined as the product resulting from the reaction of a metal ion from a soluble metal salt with amino acids with a mole ratio of one mole of metal to one to three (preferably two) moles of amino acids to form coordinate covalent bonds. The average weight of the hydrolyzed amino acids must be approximately 150 and the resulting molecular weight of the chelate must not exceed 800. The products are identified by the specific metal forming the chelate, e.g., iron amino acid chelate, copper amino acid chelate, etc.
The reason a metal atom can accept bonds over and above the oxidation state of the metal is due to the nature of chelation. In Formula I, it is noted that one bond is formed from the carboxyl oxygen. The other bond is formed by the .alpha.-amino nitrogen which contributes both of the electrons used in the bonding. These electrons fill available spaces in the d-orbitals. This type of bond is known as a dative bond or a coordinate covalent bond and is common in chelation. Thus, a metal ion with a normal valency of +2 can be bonded by four bonds when fully chelated. When chelated in the manner described the divalent metal ion, the chelate is completely satisfied by the bonding electrons and the charge on the metal atom (as well as on the overall molecule) is zero. This neutrality contributes to the bioavailability of metal amino acid chelates.
Amino acid chelates can also be formed using peptide ligands instead of single amino acids. These will usually be in the form of dipeptides, tripeptides and sometimes tetrapeptides because larger ligands have a molecular weight which is too great for direct assimilation of the chelate formed. Generally, peptide ligands, will be derived by the hydrolysis of protein. However, peptides prepared by conventional synthetic techniques or genetic engineering can also be used. When a ligand is a di- or tripeptide a radical of the formula [C(O)CHRNH].sub.e H will replace one of the hydrogens attached to the nitrogen atom in Formula I. R, as defined in Formula I, can be H, or the residue of any other naturally occurring amino acid and e can be an integer of 1, 2 or 3. When e is 1 the ligand will be a dipeptide, when e is 2 the ligand will be a tripeptide and so forth.
The structure, chemistry and bioavailability of amino acid chelates is well documented in the literature, e.g. Ashmead et al., Chelated Mineral Nutrition, (1982), Chas. C. Thomas Publishers, Springfield, Ill.; Ashmead et al., Intestinal Absorption of Metal Ions, (1985), Chas. C. Thomas Publishers, Springfield, Ill.; Ashmead et al., Foliar Feeding of Plants with Amino Acid Chelates, (1986), Noyes Publications, Park Ridge, N.J.; U.S. Pat. Nos. 4,020,158; 4,167,564; 4,216,143; 4,216,144; 4,599,152; 4,774,089; 4,830,716; 4,863,898 and others. Further, flavored effervescent mixtures of vitamins and amino acid chelates for administration to humans in the form of a beverage are disclosed in U.S. Pat. No. 4,725,427.
One advantage of amino acid chelates in the field of mineral nutrition is attributed to the fact that these chelates are readily absorbed in the gut and mucosal cells by means of active transport as though they were solely amino acids. In other words, the minerals are absorbed along with the amino acids as a single unit utilizing the amino acids as carrier molecules. Therefore, the problems associated with the competition of ions for active sites and the suppression of specific nutritive mineral elements by others are avoided. This is especially true for compounds such as iron sulfates that must be delivered in relatively large quantities in order for the body to absorb an appropriate amount. This is significant because large quantities often cause nausea and other discomforts as well as create an undesirable taste.
In view of the foregoing, it would be useful to provide a processed cereal grain or piece fortified with an amino acid chelate and method of making the same by either incorporating one or more mineral amino acid chelates throughout a processed cereal piece or by coating a processed cereal piece topically.